Transducers using piezoelectric technologies are used for precise positioning at the nanometer scale. Typically, piezoelectric devices include a ceramic that is formed into a capacitor that changes shape when charged and discharged. These piezoelectric devices can be used as position actuators because of their shape changing properties (i.e., vibrations). When such a piezoelectric device is used as a position actuator, the shape change of the ceramic is approximately proportional to an applied voltage differential across the ceramic.
Linear motors use piezoelectric generated vibrations to create continuous movement of a threaded shaft with high speed, high torque, small size, and quiet operation. An exemplary prior art linear motor includes a cylinder that supports a threaded element or nut. The cylinder includes four symmetrically positioned piezoelectric transducers to simultaneous excite the orthogonal bending modes of the cylinder at the first bending mode resonant frequency in the ultrasonic range with a plus or minus ninety-degree phase shift to generate a circular orbit. The threaded element orbits the centerline of the cylinder at the resonant frequency, which generates torque that rotates the threaded shaft that moves the threaded shaft linearly.
This linear motor typically operates at about 40 volts. However, optical systems in cell phones, cameras, or the like typically only include about a 3 volt battery. These devices simply cannot supply enough voltage to cause the motor to operate as intended without using a transformer or a DC-DC boost circuit to increase and/or step-up the voltage. The transformer adds extra circuitry, bulk, weight, and extra cost to, for example, a cell phone camera.